Method of treating tin containing materials



" orF cE 7 mrhoa or earls-tn, S'wellcn, and I 'lrostl'er, London, England 5 No prswinr. A plication May 10, 19:9, serial No. 272,920. in Norway May 18, ms

7 claims. (CI. 75-85) I In the extraction of tin from low-grade (poor) the heat required for the process will be pro ores, slags and the like, containin g,xfor example, duced. I I 40% or less of till, it is already known to. smelt Where the composition of the tin ore from the the tin-containing material with approximately mine varies, certain difllculties may be encolm 5 50% of coke, with the addition of gypsum, in va tered in reg la ing the smelting process in such a 5 shaft furnace, inthe course of which there is Way that there will not occur now and then slight driven off a (volatile) product very rich in tin. oper tin di u ba c s. s c cases it y be This method is, however, very expensive on acadvantageous to add to the charge small quanticount 01 the very great requirement of largeties 01' a carbonaceous combustible material, for

[Q sized coke, particularly in the vicinity of the example 37% of coal or coke, whereby the nec- 1o mines, where suitable combustible material as--a sary heat will be furnished for carrying through rule is obtainable only at a very high price. on of the entirepr s Without disturbancesthe other hand, owing to the low content of tin," If the charge con i Suflielent q ie of the transportation costs for the ore are too high Wr tes, the course of the process will most likely to permit transportation" to the smelter without he as follows! 18 concentration. Besides, condentration frequente furneee charge. which P r ly is 1y proves dimcult and expensive owing to the e eated befo e cha i in the upper part of complex composition of the ores. the furnace is heated by the gases ming fromi The poorer tin ores that receive consideration below to a temperature f -7 One-sulgo have a very different composition. The tin c0n-- P r m 1' h wr tes commences to distill 01!. go tent, which usually occurs in the formof s oe, 1 there is i n oxide in the charge, it will be convaries very much. The ores contain usually some ted to F88 with the formation of S02. py i es. whi h by ordinary methods a removed Somewhat deeper injthe furnace, where the by flotation, and also other sulphides. Sometimes temperature is hi her. he s phides of the char e the content of pyrites may be considerable. The will commence With the tin compound, II ores contain besides almost always varying whereby the tin is sulphidized, that 15 to say, it amounts of i and frequenuy iron oxide combines with sulphur and forms stannous sul- The present invention aims at a method, Ph and may be Smaller quantities of stannic whereby it is possible to volatilize the tin from the slflphidethe te ratu s e he a ore without previous extensive concentration, and sulphidizing becomes more lively and he tin Sill- 80 afterwards recovering-the same in the form of a Phide l M the v p r z compound rich in tin, and this without any adtion is generally finished. The vaporized tin sulditlon or nly with a small addition oi carbona- Phideis condensed outside e furnace by coolceous combustible material. 8 and is ted in dust chambers or other a In order to attain this the constituents of the arrangements If porhemof the tin sulphide is a ore, and principally t pmtes, are utilized to oxidized by oxygen present in the furnace gases, produce the heat necessary for the process and 3110: will be P which is h i d on by simultaneously to change the tiii into a volatile the gases and is collected s w y. compound In case the ores content sulphides 0f the other constituents of the charge FeS is too small, there will be added suitable sulcommences to melt a approximately drips o phides, which usually can be obtained cheap at down and for the greater part oxidized Ju t the mines, as well as free silicic acid (silica) if above the i with e aid of the ai low t ore t i t tt of t 5mm in. At this place, from the quartz which has In carrying out the method of the invention, been charged in e Shape Of ps t ere has the'tin-containing material, with the addition it been formed a Skeleton, the se-ealled l c as necessary 01' the required quantity of sulphideso n as the furnace is in normal opera i n- By containing fluxes (for example pyrites) and free e Oxidation there s 0 ed. u Strong Ke silicic acid and if desired, other fluxes, is melted ere-tion of heat 02. which rises, and FeO, which in a shaft furnace which is provided with a instantaneously combines with the 8102 of the m closed charging arrangement, and in the lower quartz. The other sulphides will also be partly. 50 part of which air is blown in. The composition oxidized in a similar manner. 'The term-silicate or the charge and the amount of the air blown in formed combines with the slag-forming mateare adjusted in such a way that the greater porrials present and forms a slag, which flows out tion of the tin will pass off with the smelting of the furnace together with the non-oxidized gases in the form of vaporous sulphide of tin and metallic sulphides (matte), for example to a fore u hearth, where slag and matte separate from each other.

The gases rising from the focus heat so strongly the charge lying above, that the reactions 5 stated above can take place. The sulphur dioxide reacts partly with the metallic sulphides (FeS) under formation of metallic oxides and elementary sulphur. If there is added to the charge a solid carbonaceous'material, preferably in the form of small lumps then $02 will also be reduced by the same. The thus generated sulphur vapor and the sulphuretted hydrogen, that may be formed with the aid of the moisture of the air, can also have a sulphidizing effect on the tin at the high temperature that is at-- tained in the furnace.

As mentioned above, the sulphide of tin leaves the furnace in the form of vapor together with the other smelting-gases. In order to avoid condensation of the sulphide of tin and its settling in the upper part of the furnace, the furnace is run in such a way, that the outgoing gases have a high temperature, for example 800-1000 C. In order to' attain this one must work with' a lower column of the charge, and one can also preheat the charge or a portion of the same, before'it is charged in the furnace.

In case not all of the tin should be sulphidized in the furnace and driven out, the-slag that is flowing out of the furnace will contain tin principally in the form of oxide compounds. In that case one can, for example in the fore hearth, blow in H28 in the molten mass (slag and matte) or also treat the charge, which still contains iron sulphides, with producer gas, coal dust or oil. Hereby thetin will be sulphidized and volatilized and can be collected jointly. However, it is desirous, of course, to regulate the composition of the charge and to carry on the operation in such 41) a way, that by the temperature, that is effected in the focus, there is slagged the smallest possible amount of Sn. v

If the-stanniferous ore contains considerable amounts of iron oxide compounds, it is often 45 advantageous to remove the same before the smelting. For that purpose the ore is finely divided and in an apparatus suitable therefor treated with a reducing gas, for example producer gas, at approximately IOU-750 C., in such a way that the greater portion of the ferric oxide is changed into magnetite (F6304). By regulating of the temperature, the gas composition and the treatment period care is taken that the reduction is not carried too far, as there otherwise also would be produced FeO, which is magnetic. The material partly reduced in this way is subjected to a magnetic separator, during which the magnetite is removed.

The tin ore freed from a large portion of the con-on oxide is briquetted together with an amount 1. A process for the recovery of tin in the form of tin sulfide from tin containing ores, slags or the like, which comprises treating the tin con- 75 taining raw material in the presence of a metal sulfide and free silica in a shaft furnace provided with tuyeres for the introduction of air blasts, while adjusting the composition of the charge and the quantity of air supplied to the furnace so as to convert the tin into tin sulfide and to produce a pyritic smelting in the furnace, -said treatment being carried out in a shaft furnace having a closed charging arrangement to prevent oxidation of the tin sulfides formed by means of air admitted from above into the furnace and withdrawing from the furnace a gaseous product containing tin substantially in the form of tin sulfides.

2. A process for the recovery of tin in the form of tin sulfide from tin containing ores, slags or the like, which comprises smelting a charge of a tin bearing material containing a metal sulfide as well as free silica or other fluxes as required and a small quantity of a solid carbonaceous material in a shaft furnace having a closed charging arrangement and provided with tuyres for the introduction of air blasts, while adjusting the composition of the charge and the quantity of air supplied to the furnace so as to obtain a conversion of the tin into tin sulfide and to produce a pyritic smelting in the furnace, oxidation of the tin sulfides formed by means of air admitted from above into the furnace being prevented by said closed charging arrangement, and withdrawing from the furnace a gaseous product containing tin substantially in the form of tin sulfides.

3. A process for the recovery of tin in the form of tin sulfide from tin containing ores, slags or the like, which comprises mixing the tin containing raw material with pyrites and free silica, adding other fluxes and a small amount of a solid carbonaceous material, preheating said mixture, charging the preheated mixture in a shaft furnace having a closed charging arrangement and provided with tuyeres for the introduction of air blasts, heating the charge while adjusting the supply of air into the furnace in such a way as to convert the tin into tin sulfide and to produce a pyritic smelting in the furnace, and withdrawing from the furnace a gaseous product containing tin substantially in the form of tin sul- 4. A process for the recovery of tin in the form of tin sulfides from tin containing ores, slags or the like, which comprises smelting a charge of tin bearing raw material containing pyrites and free silica in a shaft furnace having a closed charge arrangement and provided with tuyeres for the introduction of air blasts, while adjusting the composition of the charge and the quantity of air supplied to the furnace so as to convert the tin into tin sulfide and produce a pyritic smelting in the furnace, withdrawing from the furnace a gaseous product containing the tin substance in the form of tin sulfides, the molten mass of slag and matte flowing out from the lower part of the furnace being treated with a sulphidizing gas, so as to convert to a sulfide the tin contained therein.

5. A process for recovery of tin in the form of tin sulfide from tin containing ores, slags or the like, which comprises crushing the tin containing raw material, subjecting said crushed material to a gas reduction in such a way that iron oxide present therein isreduced to magnetite, separating the magnetite from the other constituents, I

mixing said other constituents with pyrites, and quartz, and then briquetting the mixture, charging said mixture in a shaft furnace having a closed charging arrangement and provided with tuyeres for the production of air blasts, while adjusting the quantity of air introduced into the furnace so as to obtain a conversion of the tin into tin sulfide and to produce a pyritic smelting in the furnace, and withdrawing from the furnace a gaseous product containing tin substantially in the form of tin sulfides.

6. A process for recovery of tin in the form of tin sulfide from tin containing ores, slags or the like, which comprises crushing the tin containing raw material, subjecting said crushed material to a gas reduction in such a way that iron oxide present therein is reduced to magnetite, separating the magnetite from the other constituents, mixing said other constituents with pyrites and quartz, and then briquetting the mixture, charging said mixture in a shaft furnace having a closed charging arrangement and provided with tuyeres for the introduction of air blasts, while adjusting the quantity of air introduced into the furnace so .as to obtain a conversion of the tin into tin sulfide and to produce a pyritic smelting in the furnace, and withdrawing from the furnace a gaseous product containing tin substantially in the form of tin sulfides.

'7. A process for the recovery of tin in the form of tin sulfide from tin containing ores, slags or the like, which comprises mixing the tin containing raw material with pyrites and free silica, adding other fluxes, pre-heating said mixture, charging the pre-heated mixture in a shaft furnace having a closed charging arrangement and provided with tuyeres for the introduction of air blasts, heating the charge while adjusting the supply of air into the furnace in such a way as to convert the tin into tin sulfide and to produce a pyritic melting in the furnace, and withdrawing from the furnace a gaseous product containing tin substantially in the form of tin sulfide.

FREDRIK CARLSSON. FREDRICK TROS'I'LER. 

